Primary dysmenorrhoea (period pain): causes, treatment and when to see a GP

Dysmenorrhoea simply means painful periods. Doctors divide it into two types. NICE Clinical Knowledge Summaries defines primary dysmenorrhoea as period pain that occurs without any identifiable underlying pelvic problem, and secondary dysmenorrhoea as pain caused by an underlying condition such as endometriosis, fibroids or pelvic inflammatory disease, or by an intrauterine device (IUD).

The word primary is not a judgement of how bad the pain is. Primary period pain can be severe enough to keep someone off school or work, and NICE CKS notes that dysmenorrhoea can adversely affect quality of life and lead to missed days. The distinction matters because the next steps differ: primary pain is managed with pain relief and hormonal options, while secondary pain needs the underlying cause investigated.

The NHS describes period pain as a sharp pain or dull ache in the tummy, often painful cramps that spread to the back and thighs, around the start of a period or just before it. NICE CKS gives a similar picture for primary dysmenorrhoea: pain beginning shortly before bleeding starts, mostly in the lower abdomen, sometimes radiating to the back and inner thighs, and easing as the period goes on.

Other symptoms can travel with it. NICE CKS lists nausea, vomiting, diarrhoea, tiredness, irritability, dizziness, headache and lower back pain. These are common companions of the cramping and do not by themselves mean something else is wrong, although they can make a bad day worse.

• Cramping pain in the lower tummy beginning just before or at the start of bleeding.

• Pain that spreads to the lower back or the inner thighs.

• Pain that tends to be worst in the first day or two and settles afterwards.

• A normal pelvic examination when examined by a doctor, which is typical of primary dysmenorrhoea.

The NHS says period pain happens when the womb tightens during a period and is often a normal part of the menstrual cycle. NICE CKS gives the mechanism: the womb lining produces prostaglandins during menstruation, which cause the muscle of the womb to contract and produce pain.

NICE CKS lists several risk factors for primary dysmenorrhoea or for more severe episodes: starting periods at an earlier age, heavy menstrual flow, never having given birth, and a family history of painful periods. Having one of these does not predict what any individual will experience, and many people with none of them still have significant pain.

This is the central question for a clinician. NICE CKS says secondary causes must be excluded before primary dysmenorrhoea is diagnosed. Secondary dysmenorrhoea often starts after several years of painless periods, the pain may not follow the period closely and can continue after bleeding stops or be present throughout the cycle, and other gynaecological symptoms such as pain during sex are often present.

The NHS lists conditions that can cause painful periods: endometriosis and adenomyosis (womb-like tissue growing in other places), fibroids, and pelvic inflammatory disease. An IUD can also cause period pain, particularly during the first 3 to 6 months after it is put in. NICE CKS also lists features that point to a more serious cause and need specialist assessment, including a positive pregnancy test with vaginal bleeding, a pelvic or abdominal mass, an abnormal cervix, and persistent bleeding between periods or after sex.

There is no single test for primary dysmenorrhoea. The assessment is mostly a conversation: when the pain started, how it relates to bleeding, how long it lasts, how much it affects daily life, and whether there are other symptoms such as pain during sex, bleeding between periods or bowel and bladder changes. A clinician may examine the abdomen and, depending on the history, the pelvis.

The NHS says a GP may refer you to a gynaecologist if period pain does not get better or if they think a condition such as fibroids may be responsible, and that tests such as an ultrasound scan may be used to find the cause. NICE CKS says referral should be arranged if symptoms are severe and have not responded to initial treatment within 3 to 6 months, or if there is doubt about the diagnosis.

The NHS lists a warm bath or shower, a heat pad or hot water bottle wrapped in a tea towel on the tummy, massaging the tummy and back, gentle exercise such as yoga, swimming, walking or cycling, and painkillers such as paracetamol or ibuprofen. It adds that cutting down on alcohol and not smoking may help. NICE CKS also supports local heat and transcutaneous electrical nerve stimulation (TENS).

If simple measures are not enough, the NHS says a GP may recommend an anti-inflammatory medicine such as naproxen, flurbiprofen or mefenamic acid, a TENS machine, or contraception such as the pill, implant or injection, which thins the womb lining and can make periods lighter and less painful. NICE CKS describes hormonal contraception as an alternative first-line treatment for those who do not wish to conceive, with the added benefit of contraception. Medicines should be used as advised by a pharmacist or prescriber, as anti-inflammatory tablets are not suitable for everyone.

The NHS says to ask for an urgent GP appointment or get help from NHS 111 if pelvic pain or period pain is severe or worse than usual and painkillers have not helped. Sudden severe pelvic pain, fainting, or heavy bleeding with dizziness should not be waited out. If you could be pregnant, new pain with bleeding needs urgent assessment, and if you are very unwell call 999 or go to A&E.

The NHS also lists reasons to see a GP in the usual way: periods becoming more painful, heavier or irregular, pain that stops you doing everyday things, pain during sex or when peeing or pooing, bleeding between periods, changes in peeing or pooing, a swollen tummy, loss of appetite, or losing weight without trying.

Most people with primary dysmenorrhoea never need anything beyond the GP surgery or a sexual health or contraception service, where pain relief, hormonal options and an IUD review are all available. Specialist gynaecology on the NHS generally follows a GP referral, and it is more likely when pain is severe, resistant to first-line treatment or suggests a secondary cause.

Some people choose to see a private gynaecologist, for example when they want an earlier scan or a more detailed discussion after treatment has not helped. The aim of the appointment is the same: to work out whether this is primary pain or whether a condition such as endometriosis or adenomyosis is present. A symptom diary covering several cycles, with pain scores, bleeding pattern and which treatments were tried, makes either appointment more productive.